Homozygous elastase, neutrophil expressed knock-out (Elanetm1Sds) mice have increased susceptibility to sepsis, morbidity, and mortality following intraperitoneal injection of Gram-negative bacteria. These mutant mice may be useful in studies of immunity and immunology.
Steven D Shapiro, University of Pittsburgh
Homozygous mice are viable, fertile and phenotypically normal in the absence of inflammatory stress. Homozygotes do not express the targeted gene in bone marrow myeloid cells. Homozygous mice have increased susceptibility to sepsis, morbidity, and mortality following intraperitoneal injection of Gram-negative (e.g. (K. pneumoniae and E. coli), but not Gram-positive (e.g. (S. aureus), bacteria. Despite this, mutant mice are not at increased risk to spontaneous infection. Although neutrophil, T cell, and macrophage migration/recruitment to the site of infection is unaffected in homozygous mutant mice, neutrophils show impaired bactericidal activity. Further, homozygous mice treated with a broad-spectrum inflammatory stimulus (zymosan) have impaired leukocyte firm adhesion and transmigration as well as reduced pro-inflammatory cytokine production. Upon exposure to cigarette smoke, homozygous mice are protected from the accumulation of neutrophils and macrophages in the lungs, as well as the development of airspace enlargement. These mutant mice may be useful in studies of immunity and immunology, including host defense against Gram-negative bacteria, granulocyte/neutrophil function, sepsis, and cigarette smoke-induced emphysema.
A targeting vector containing a neomycin phosphotransferase cDNA driven by the phosphoglycerate kinase promoter (PGK-neo) was used to replace exon 2 (which contains the histidine residue of the catalytic triad) of the endogenous gene. The construct was electroporated into 129X1/SvJ-derived RW4 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6J blastocysts. The resulting chimeric animals crossed to 129X1/SvJ mice, and the strain was maintained on this background for an unknown number of generations. The donating investigator reports that mutant mice were then mated to "C57BL/6 mice from Charles River" (C57BL/6NCrl) (see SNP note below) for at least 10 generations before arrival at The Jackson Laboratory. Upon arrival, male and female mice were bred together.
A 32 SNP (single nucleotide polymorphism) panel analysis, with 27 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. While the 27 markers throughout the genome suggested a C57BL/6 genetic background, at least 2 of 5 markers that determine C57BL/6J from C57BL/6N were found to be segregating. These data suggest the mice sent to The Jackson Laboratory Repository were on a mixed C57BL/6J ; C57BL/6N genetic background.
|Allele Name||targeted mutation 1, Steven D Shapiro|
|Allele Type||Targeted (Null/Knockout)|
|Gene Symbol and Name||Elane, elastase, neutrophil expressed|
|Strain of Origin||129X1/SvJ|
|Molecular Note||The insertion of a neomycin selection cassette replaced exon 2, which encodes the histidine residue of the catalytic triad. Northern blot analysis of total RNA obtained from bone marrow myeloid cells showed that transcript encoded by the targeted allele was absent. Reprobing of the blot showed that the expression of the closely linked proteinase 3 was unaffected by the targeting event. An absence of elastocytic activity derived from the targeted locus was determined via kappa-elastin zymography.|
|Mutations Made By|| |
Steven Shapiro, University of Pittsburgh
When maintaining a live colony, these mice are bred as homozygotes. While the publications indicate mutant mice are not at increased risk to spontaneous infection, The Jackson Laboratory maintains homozygous colonies in microisolator ventilation.
When using the NE- mouse strain in a publication, please cite the originating article(s) and include JAX stock #006112 in your Materials and Methods section.